President Trump plans to nominate former airline executive Stephen M. Dickson to head the Federal Aviation Administration, according to a White House statement on Tuesday.

Dickson, a former executive at Delta Air Lines, would replace acting FAA Administrator Daniel K. Elwell.

The FAA has been under interim leadership since January 2018, following the departure of Michael Huerta, whose five-year term had expired.

The announcement comes as the agency faces increasing criticism and scrutiny over what some viewed as its slow response to the crash of an Ethio­pian Airlines jetliner and questions over whether it did enough to ensure the aircraft involved in the crash, a Boeing 737 Max 8, was safe to fly.

The March 10 crash, which killed all 157 people aboard, was the second involving the Boeing 737 Max 8 in less than five months.

Also Tuesday, Transportation Secretary Elaine Chao, who had been a supporter of Dickson getting the permanent post, asked her department’s Office of Inspector General to launch an audit to “compile an objective and detailed factual history” of activities that led the FAA to certify the 737 Max 8.

Chao’s announcement of the request emphasized that Boeing had applied for its certification for the plane in January 2012, and that the FAA granted it in March 2017 — shortly after she took over as secretary.

Rep. Peter A. DeFazio (D-Ore.), chairman of the House Transportation Committee, and Rep. Rick Larsen (D-Wash.), who heads the aviation subcommittee, on Tuesday also asked the inspector general to examine questions concerning the FAA’s approach to certifying the 737 Max 8.

Among them: how new automated features of the plane were “tested, certified, and integrated”; what safety assumptions “led to the FAA’s decision not to revise pilot training programs and manuals” to reflect the automated features; how the FAA’s delegation of authority to Boeing may have affected the certification process; and what corrective actions have been taken since the initial accident in October 2018.

Sen. Richard Blumenthal (D-Conn.) called Chao’s request “inadequate and incomplete.” He asked the inspector general to investigate the Trump administration’s “lackluster” response to an earlier crash in Indonesia last year, as well as whether FAA or Boeing employees had engaged “in any unethical, improper or criminal activity during the certification process.”

A spokesman for the inspector general said the office is preparing to launch an audit. Asked what time frame and areas of inquiry would be covered, the spokesman said the “scope and objectives”of the review are being determined.

Elwell, a former American Airlines pilot, has been acting administrator since Jan. 7, 2018. He also served as deputy administrator and in other capacities at the FAA.

Some critics have questioned why it has taken so long to fill the important job. Trump wanted his longtime personal pilot, John Dunkin, at the helm of the agency, but the president lacked the needed support on Capitol Hill for the nomination, which contributed to delays in nominating a permanent administrator, according to a former FAA official.

“He wanted his guy there. There’s no question about that. It became something of a standoff,” according to the former official, who spoke on the condition of anonymity to discuss the process candidly.

Dickson, who must be confirmed by the Senate, previously served as an airline captain and senior vice president for flight operations at Delta Air Lines. In that role, he was responsible for the safety and performance of the airline’s global flight operations. He was also an Air Force pilot.

Dickson graduated from the U.S. Air Force Academy near Colorado Springs, and also holds a law degree from the Georgia State University College of Law.

The Justice Department’s criminal division is looking into the Boeing 737 Max 8, though the parameters of that inquiry remain unclear.

Apart from the audit, the Inspector General’s Office of Investigations, which handles criminal and other matters, has also sought details about FAA’s certification of the plane and its training materials, according to a person with knowledge of that effort.

Chao said the audit she requested is necessary “to help inform the Department’s decision-making and the public’s understanding, and to assist the FAA in ensuring that its safety procedures are implemented effectively.”

“Safety is the top priority of the Department, and all of us are saddened by the fatalities resulting from the recent accidents involving two Boeing 737-MAX 8 aircraft in Indonesia and Ethi­o­pia,” Chao said.